需要更改CALayer类对象的大小和位置 [英] Need to change size and location of CALayer class objects
问题描述
我正在尝试复制Apple提供的名为AVCam的示例应用程序的所有功能:
I am trying to copy all of the functionality of this example app provided by Apple called AVCam: https://developer.apple.com/library/ios/samplecode/AVCam/Introduction/Intro.html#//apple_ref/doc/uid/DTS40010112-Intro-DontLinkElementID_2
我唯一遇到的麻烦是更改UIView对象的大小和位置.问题是我使用的是苹果的示例代码，对我来说只是没有意义.
The only thing I am having trouble with is changing the size and location of a UIView object. The problem is I am using apple's sample code and it's just not making sense for me.
Apple提供了这个示例VC，我将其称为MediaCapturePreviewView.这是头文件代码:
Apple provides this sample VC that I have called MediaCapturePreviewView. Here is the header file code:
#import <UIKit/UIKit.h>
@class AVCaptureSession;
@interface MediaCapturePreviewView : UIView
@property (nonatomic) AVCaptureSession *session;
@end
这是主文件代码:
#import "MediaCapturePreviewView.h"
#import <AVFoundation/AVFoundation.h>
@implementation MediaCapturePreviewView
- (void)drawRect:(CGRect)rect
{
// Drawing code
}
*/
+ (Class)layerClass
{
return [AVCaptureVideoPreviewLayer class];
}
- (AVCaptureSession *)session
{
return [(AVCaptureVideoPreviewLayer *)[self layer] session];
}
- (void)setSession:(AVCaptureSession *)session
{
[(AVCaptureVideoPreviewLayer *)[self layer] setSession:session];
}
@end
然后，在我应用程序的中央View Controller中，导入了"MediaCapturePreviewView"头文件.我刚刚给你看的最后但并非最不重要的一点，在中央视图控制器的主文件中，我在界面区域中有一个IBOutlet，如下所示:
Then in my app's central View Controller, I have imported the header file of "MediaCapturePreviewView" that I just showed you. Last but not least, in my central view controller's main file I have an IBOutlet in the interface area that looks like this:
@property (nonatomic, weak) IBOutlet MediaCapturePreviewView *previewView;
以上IBOutlet已连接到Interface Builder中覆盖整个iPhone屏幕的UIView对象.
The above IBOutlet has been connected to a UIView object in Interface Builder that covers the entire iPhone screen.
这是当您点击拍照"时如何使用previewView的一个小示例.按钮:
And then here is a small example of how previewView is used when you tap the "take a picture" button:
- (IBAction)snapStillImage:(id)sender
{
dispatch_async([self sessionQueue], ^{
// Update the orientation on the still image output video connection before capturing.
[[[self stillImageOutput] connectionWithMediaType:AVMediaTypeVideo] setVideoOrientation:[[(AVCaptureVideoPreviewLayer *)[[self previewView] layer] connection] videoOrientation]];
我已经尝试在上述方法调用之后立即添加此代码，但这无济于事:
I have tried adding in this code right after the above method calls but it is not helping:
_previewView.frame = CGRectMake(0, 0, self.view.bounds.size.width, self.view.frame.size.height/2);
我知道您可以编辑CALayer类对象的属性，例如框架，边界和位置，但是我只是被卡住了，不知道我到底需要在哪里编辑这些东西.
I know that you can edit properties for CALayer class objects like frame, bounds, and position but I'm just stuck and don't know where exactly I need to edit these things.
这是拍照时当前UIView的外观:
This is what the current UIView looks like when taking a picture:
这就是我需要的样子:
我基本上需要它完全占据iPhone屏幕的前50％.
I basically need it to take up exactly the top 50% of the iPhone's screen.
非常感谢您的帮助.
推荐答案
视频具有适合iPhone屏幕的默认捕获比率.如果尝试将其缩放到其他比例(例如半屏)，则会得到失真的图像或裁剪的图像.
The video has a default capture ratio which fits the iPhone's screen. If you try to scale it to a different ratio (such as half screen) you will get a distorted image or a cropped one.
为了实现您要执行的操作，我认为使用包含所需控件(例如拍照按钮)的 UIView 覆盖屏幕的一半会更容易.)，然后使用以下方法将捕获的全屏图像裁剪为其一半大小:
In order to achieve what you're trying to do I think it would be easier to just cover up half of the screen with a UIView containing the controls you want (such as take a photo button) and then just crop the captured full screen image to half its size with something like this:
CGRect clippedRect = CGRectMake(0, 0, self.view.frame.size.width,self.view.frame.size.height/2.0);
CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], clippedRect);
UIImage *newImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
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